Pneumatic tool construction



May 18, 1954 R. E. DOEDEN PNEUMATIC TOOL CONSTRUCTION Filed May 24. 1951 LQIU'NITEDi[T STATES PATENT 1 OFFICE QL,

.i 'Y *i l 4, .l,if.iffe;{67g,sflff l l r`1v 1-u;n.1 a irrreh'roor, oNs'raUcrIoN Y Roland E. Droeden,` Crete, Ill., assignor to Mall Tool Company, Chicago, ,111., acorporation voi .,Illinois i; M y p Application ivresse, 1951, sen-.irai No. 228,034 y' zcleims. (crisilen v l r, ,.V Y v Vt .ei This inventionrelates .to improvements in a As shown in the drawings: pneumatic tool, more particularly, it :has todo *In Figure 1 the reference numeral l0 indicates with a'combination sound absorbing and air nlgenerally a pneumatic screwdriver of the rotary tering member in the form of a ring of porous vane type, wherein air under pressure impinges material disposed across the discharge air pas 5 against the blades or varies, which are slideably` sageof a pneumatic tool and effective to' reduce mounted in radial grooves of the rotor and causes tl" noisev incident to the operation of the tool therotor to-rotate, and, through a suitable-drive 'adto'filter the air passing'therethrough. mechanism, to rotate the effective end ofthe `The air that is discharged from a typical pneu# screwdriver. I y

matic tool makes a shrill, high-pitched noisethat l0 the Yembodiment chosen for illustrating the is very objectionable to the operator of the tool. device of this invention, air under pressure 'en- The noise is due ichiefly to-the high velocity `et ters through a Yport l2 rearwardly located inthe the Aair as it passes over the operating mechanism tool'l I0; A valve i4 positioned within the tooli of the tool and throughthe exhaust ports. It I0 with its stem extending therefrom to 'be' ac'' is, therefore, an important object of the present tuated through a hand-operated lever l5, con-` invention'to provide means for decreasing the frOlSl theflOW 0f nir frcm lie'lccr l2 ntc 9 D9S` velocityfof the air through the eithaustpassa'ges Sage 'I6 Which in flow communication with of `a .pneumatic tool. two alignedpassages I3 and I9 in thebody of' the AAnother object of this invention is to provide i001 and Dort 20 of a Cylinder 29 which is'also means for absorbing or cancelling out sound in the tool l0. It Will be understood thatY the Waves incident to the operation of a pneumatic location, size or extent ofthe inlet air passages toolwith the said means simple in construction described'- above form no part of this invention, andi` veryf easily installed in the tool. beingillustratedonly toshowan operative mechn According to the general features of the presanism; ent invention, there is preferably provided an an- 25 Theeirpassage 20 directs air to the inlet side nularri'ng of porous YmetaLjsuch as sintered of a "rotor `22"'disposed within the cylinder. 29;' bronze, which is arrangedV to A'be -positionedinthe and `the'airpaus'es the rotor to rotate around its path of now ofy the high velocity air as it leaves aXiS rand, thrcugh genre 24 end a coupling 25 the motor assembly of the pneumatic tool. While which form the internal drive mechanism of. the

the sound deadening device of the present inven- 3@ 001 l0, t0 drive a Screwdriver 2l in a manner tion is particularly described as a porous bronze Well known in the art. It should be noted that ring adapted for use with small portable power a plurality 0f Nenes 23 are Slideebly mounted in tools, it is to be understood that other materadial grooves 22a of the rotor 22, as best Seen rials, e. g., synthetics, laminated crimp paper, in Figure 2, and thereby provide the means of other metals, etc., can be advantageously used in Operating the rotor 22 and its corresponding drive this instauation Where the noise level is high due mechanism as hereinafter further described. to high velocity air. As best seen in Figure 2, the rotor 22 mounted Still a further object of this invention is to concentric with the housing 3d and eccentric provide a means of deadening noise in the operarelative to the bore of the cylinder 29 creates a tion of a pneumatic tool while the said means also crescent shaped chamber 4l, which receives live operates as a filter member on the air passing ail' et One end through DcrUS 2@ and eXhauStS through the said e001, through port 30 of the cylinder the longitudinal Other and further features, objects and adrecesses 32 of housing 34 and the passage 33 of vantages of the present invention will be apparhousing 35 A rcSilcni Seel ring 40, diSpOSed ent to one skilled in the art from the renewing between the housing members 34 and 35. is prodetailed description taken in connection with the vided With cut-Out portions 4l to conform to wcompanying drawings, the shape and location of the recesses 32 and 33.

In the drawings: Thus it is seen that the vanes form pockets in Figure 1 is a partially sectioned side elevathe chamber 4l, each Docket being ccnneced in tional view showing in a preferred embodiment turn to the air under pressure and to the exhaust the novel noise deadening device of the present inas the rotor revolves in response to the air under vention mounted in a pneumatic screw driver. DreSSuIe acting 0n the Successive vanes.

Figure 2 is a sectional view taken on line As shown in Figure l, a preferred embodiment II--II of Figure 1. of this invention comprises an annular metal Figure 3 is a free body view of a noise deaden- 55 member 43 positioned against a shoulder 45 ing device of this invention. formed by an annular recess 46 at the end of the housing 34. This ring is held in position by the assembly of the various housing members.. It may be made of any relatively rigid porous` material but in a preferred embodiment it is made of sintered bronze. However, the ring need not be made of metal as long as it is relatively rigid so that exhaust lair will not distort Vit and so long as it provides aiseries of tortuous paths for the exhaust air (without materially raising the back pressure) to effect the noise deadening feature and filter the exhausting air. .The porous ring may thus be made of any relatively rigid acoustical material that will absorb sound waves or will cancel them out by ,interferencepf 4soun-d Waves from the same source and also prevent the passage of ne granular particles.

It should be further noted that the ring 43 serves as an air iilter in the tool, as the air `passes therethrough in the operation of the tool. This feature is particularly vdesirable when 4the .tool motor-is idling with-theair supply shut off. Under these conditions the motor acts as a fan to suck air back into the tool through the exhaust passages. Frequently, the air sucked in is-conr taminated by the dustcreated in the operation of the tool. such as that encountered in a grinding operation. Thus, it should be apparent that this invention is a highly useful device which serves the compound function of noise deadening and air .ltering The operation of the present invention will be apparent rfrom the foregoing description. It is to lbeparticularly noted that the porous ring is verysimple indesign, is very easily installed, and replaced,.and need not haveany structural value.

`It will be understood that modilications and variations ymay be effected .without departing from the scope of the novel concepts of the present invention.

I claim as myinvention:

.1. In combination in a pneumatic tool, a generally tubular housing having separable .fore and rear sections, a rotary air motor mounted in the rear sectionof said housing, a drive mechanism coupled to said motor contained within the fore section of said housing, annularly arranged air exhaust passages longitudinally disposed within the housing connecting the outlet side of said air motor to atmosphere and carrying the exhaust air past the drive mechanism, said air exhaust passages discharging forwardly of the housing, and a relatively rigid porous member of sintered material mounted between the housing sections and across said yexhaust .passages .in .the path of flow of the exhausting air whereby to reduce the .noise incident to operation of the tool and to lter air passing through said passages.

2. In combination in a pneumatic tool, a gen- .erally-tubulai` housing having separable fore and section of the housing, a relatively rigid porous member of sintered material positionedin the annular recess, said member thereby being mountedacross said exhaust 1passages inthe path of flow of the exhaust air whereby to reducethe noise incident to operation of the tool and to lter air passing through said passages.

References Cited in the iile of this patent UNITED STATES PATENTS Number Name Date 646,702 Keller Apr. 3, 1900 1,115,704 Manes Nov.3, 1914 1,514,007 Moore et al Nov.-4, 1924 "1,727,718 Kinsey Sept. 1.0, 1929 1,979,537 Elliott Nov. 6,1934 2,048,993 Claiey et al ,July 28, 1936 y2,211,814 Geeraert et al. .Aug.'20, 1940 2,220,641 Davis Nov. 5, 19.40.

FOREIGN PATENTS Number Country VDate .923,627 .France Feb. 24, 1947 

